The URL can be used to link to this page

Home My WebLink AboutFT Pierce Monopole Geotech Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com Geotechnical Investigation Ft. Pierce 2 Off Digiorgio Road Fort Pierce, St. Lucie County, Florida ECA Project No. T1542b SUBMITTED TO: B+T Group 1845 Town Center Boulevard Fleming Island, FL 32003 PREPARED BY: Environmental Corporation of America 1375 Union Hill Industrial Court, Suite A Alpharetta, GA 30004 Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com May 8, 2019 B+T Group 1845 Town Center Boulevard Fleming Island, FL 32003 Attention: Mr. James McNicol Subject: Geotechnical Investigation Report Ft. Pierce 2 Off Digiorgio Road Fort Pierce, St. Lucie County, Florida ECA Project No. T1542b Dear Mr. McNicol: Environmental Corporation of America (ECA) is pleased to submit this report of our geotechnical investigation for the proposed project. Our services were provided as authorized by B+T Group via a purchase order approval dated April 9, 2019. This report presents a review of the information provided to us, a description of the site and subsurface conditions, and our recommendations. The appendices contain a Site Location Map, Boring Location Plan and a Boring Log. Purpose and Scope of Work The purpose of this investigation was to obtain specific subsurface data at the site and to provide geotechnical-related parameters for the design and construction of the foundation for a new monopole tower. Our scope of work included the following: One (1) soil test boring was drilled to a depth of 60 feet below the ground surface (bgs). Figure 1 shows the Site Location Map. Figure 2 shows the Boring Location Plan. Standard penetration tests (SPTs) were conducted to obtain soil samples and SPT N-values, in accordance with ASTM D-1586. The depth to groundwater, if any, was measured in the boring after drilling was completed. Mr. James McNicol Page 2 Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com The soil samples were visually classified in accordance with ASTM D-2488 and a boring log was prepared. The soil conditions were evaluated by a registered professional engineer and this geotechnical report was prepared with our recommendations. Natural moisture contents (WCN) measurements were conducted on selected soil samples in accordance with ASTM D-2216. We have recommended design parameters and settlements based on the SPT N-values, an examination of the soil samples, and our experience with similar soil conditions and structures. Project Information We were provided with a project site survey prepared by Stonecypher Surveying, Inc., and dated November 14, 2018. The proposed tower would be located off Digiorgio Road, Fort Pierce, St. Lucie County, Florida. In general, the proposed tower compound would be located within a relatively flat terrain with a surface elevation near 17 feet Above Mean Sea Level (A.M.S.L.) within the proposed 50-foot by 50-foot (2,500 square feet) lease area. The ground surface within the proposed lease area is covered with low grass. We understand that plans include constructing a 150-foot tall monopole, approximately as shown on Figure 2 in Appendix A. We assume that the equipment building/cabinet will be a pre-fabricated structure supported on a perimeter grade beam, spread footing or turndown slab. The project also includes the construction of a 30-foot wide non-exclusive access and utility easement. Field Drilling Work The fieldwork was conducted on May 2, 2019. Information obtained from the boring was used to help us evaluate the subsurface conditions and to assist in formulating our recommendations. The tower center was staked at the time of our site visit. Local Geology and Subsurface Soil Conditions (Boring B-1) The geology of the site is best described by the Geological Map of State of Florida, Florida Geological Survey, and Florida Department of Environmental Protection, as being within Anastasia Formation, with the primary soil type of Limestone. The subsurface conditions were explored with one soil test boring, drilled approximately as shown on Figure 2. In general, from ground surface and extending to the depth drilled of 60 feet below ground surface (bgs), soils encountered consisted initially of Fill material manually described as fine silty Sand, underlain by medium compact to compact dense poorly graded Sand (SP) with trace amounts of organic matter and medium compact clayey Sand (SC) to an approximate depth of 8.5 feet, underlain by very loose to medium compact fine silty Sand (SM) and loose to very Mr. James McNicol Page 3 Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com compact dense fine to medium coarse silty Sand (SM) with trace amounts of shell fragments to the explored depth of 60 feet. The N-values are shown on the attached boring log and ranged from 19 to 32 blows per foot (bpf) for the upper poorly graded sand and clayey sand layers, from 3 to 17 bpf for the middle silty sand layers, and from 10 to over 50 bpf for the lower silty sand with shell fragment layers. Natural moisture content (WCN) measurements were conducted on selected soil samples and ranged from 7.0% to 24.5%. Groundwater Level Condition At the time drilling (ATD), a groundwater level condition was encountered at a depth of 4.4 foot (53 inches). It should be noted that groundwater level observations made within mostly cohesive soils during drilling could be misleading. It should be anticipated that the groundwater level will fluctuate due to seasonal climatic changes during the year. To determine actual groundwater level measurements, groundwater levels should be measured using observation wells installed for prolonged periods. Foundation Construction Recommendations The subsurface conditions are suitable for the support of the proposed tower using a deep foundation system. Deep Foundation System Based on our review of the subsurface soil conditions encountered in the boring, we offer the following average soil parameters for the design of the new tower. Depth (feet) Unit Weight *wet (pcf) Friction Angle (deg) Soil Cohesion Su (psf) Kp Skin Friction fS (psf) Bearing Pressure qALL (psf) Soil Modulus KH (pci) 0-5.5 120 34 0 3.54 105 - 104 5.5-13.5 120 / 58 32 0 3.25 175 - 104 13.5-18.5 100 / 38 27 0 2.66 215 - 65 18.5-33.5 110 / 48 32 0 3.25 365 3,000 205 33.5-43.5 110 / 48 30 0 3.00 465 3,000 205 43.5-60 125 / 63 36 0 3.85 780 7,500 520 A safety factor of 2 is used for allowable skin friction (fS). A safety factor of 5 is used for allowable soil bearing pressure (qALL). *Below the groundwater level designer should consider the buoyant unit weight (b) = wet – water. For KA calculation project designer, should consider KA=1/KP. Mr. James McNicol Page 4 Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com The proposed drilled shaft should be design using a combination of skin friction and point bearing forces. Total drilled shaft foundation settlement should be limited to 0.50-inch or approximately 0.60% of the drilled shaft diameter (D). Final shaft diameter (D) and embedment length (L) will depend upon final tower loading conditions. Drilled shaft lateral deflection should not exceed a maximum value of 0.25-inch. For these foundations ECA recommends a minimum concrete strength (f’c) of 4,000 psi with a corresponding mix design slump between 4 and 8 inches. As an alternative and based on the existing soil conditions, project designer may consider using multiple driven piles under a mat foundation. Driven piles may range from 12 to 16 inches in diameter. The following table presents the relationship between the ultimate driven pile compression load capacity, pile diameter (Diam.), and embedment length (L). Pile Length (L) (feet) Ultimate Driven Pile Compression Load Capacity Analysis (Kips) Pile Diameter (Diam.) (inches) 12-inches 14-inches 16-inches 50 215 275 345 55 255 325 405 Note: A safety factor should be applied to the provided ultimate load. Building Foundations The proposed equipment building can be supported on a perimeter grade beam, spread footing or turndown slab foundation. For the design of the building foundation the soils are capable of a maximum net allowable soil bearing pressure (qALL) of 2,000 psf. A minimum depth of foundation (Df) of 1.5 feet below final grades should be considered. Total and differential settlements should be less than 1/2-inch and 1/4-inch, respectively. For the design of floor concrete slabs, the designer may consider a modulus of subgrade reaction for compacted backfill material (Ks) of 85 pounds per cubic inch (pci). Bearing pad should be prepared and compacted prior to placing any concrete. Contractors should verify the Fill Placement section of this report. Soil Site Class Based on our site evaluation and the information provided by the International Building Code (2009), to perform a dynamic analysis the clients design engineer should consider that the soils at the site fall under Soft Soil Profile and Site Class E. Mr. James McNicol Page 5 Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com Liquefaction Analysis for Boring B-1 As shown on the attached boring log, from approximately 13.5 feet and 18.5 feet bgs, ECA encountered a very loose silty sand soil. A liquefaction analysis was performed for the general profile obtained at the site using Seed and Idriss (1971) conventional procedure, an earthquake magnitude (M) of 7.5 (Richter Scale), and an average ground surface acceleration (g) coefficient of 0.09g, as described by the Telecommunications Structural Standard (TIA-222-G) and dated August 2005. For the described depth, a liquefaction safety factor of 0.98 was encountered. In general, a minimum safety factor of 1.20 is considered safe for liquefaction analysis. Foundation Excavations A groundwater level was encountered near the anticipated depth of foundation. Therefore, prospective contractor would need to consider excavation dewatering. To avoid softening of the shallow soils exposed at the foundation bearing level, excavations should not be left open for extended periods prior to placing reinforcing steel and concrete. If rain or freezing weather is expected, excavations should not be completed. Leaving the excavations at least 1-foot above final grade should protect the bearing soils from deterioration. If the excavation must remain open overnight or if rainfall becomes imminent while the bearing soils are exposed, we recommend that a 2 to 4-inch thick "mud-mat" of "lean" (2,000 psi) concrete be placed on the bearing soils before the placement of reinforcing steel. If the bearing soils are softened by surface water intrusion or exposure, the softened soils must be removed from the foundation excavation bottom immediately prior to placement of concrete. Fill Placement If required, borrow materials for fill, unless otherwise specified, should consist of essentially granular material (GM, GP, GM, GC, SW, SP or SM Unified Soil Classification System); A-2-6 or better, AASHTO Classification, as approved by the Project Geotechnical Engineer. In-situ sandy soils could be use as backfill. These should be free from vegetation and should not contain rocks greater than 6 inches in size. The amount of fill required for this project depends on the planned final grades. Any fill or backfill required to attain finished grade should be placed in layers not exceeding 8 to 10-inch thick lifts and compacted to not less than 95% of the Modified Proctor Maximum dry density, as determined by method (ASTM D-1557). The soil moisture content should be close to the optimum moisture content. All required fill should meet the specified compaction criteria. Mr. James McNicol Page 6 Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com ECA does not know the capability of the surficial soil to support pavements. However, we suggest that the upper soils be replaced by granular fill in areas of heavy traffic to improve the subgrade support capabilities and moisture sensitivity. Field density tests should be conducted at routine intervals as the fill is being placed to verify that adequate compaction is achieved. Prior to placing any new fill, any soft or loose near surface soils should be removed and the area Proof-Rolled with a heavy vehicle or a heavy compaction vibratory roller to confirm that any unsuitable soil conditions have been discovered. Basis for Recommendations The subsurface conditions encountered at the boring location is shown on the Boring Log in Appendix B. The Boring Log represents our interpretation of the subsurface conditions based on the field logs and visual examination of field samples by an engineer. The lines designating the interface between various strata on the Boring Log represents the approximate interface locations. In addition, the transition between strata may be gradual. The water level shown on the Boring Log, if any, represents the condition only at the time of our exploration. The recommendations contained herein are based in part on project information provided to us and only apply to the specific project and site discussed in this report. If the project information section in this report contains incorrect information or if additional information is available, please let us know so that we may review the validity of our recommendations. Regardless of the thoroughness of a geotechnical investigation, there is always a possibility that conditions between borings will be different from those at specific boring locations and that conditions will not be as anticipated by the designers or contractors. In addition, the construction process may itself alter soil conditions. Therefore, experienced geotechnical personnel should observe and document the construction procedures used and the conditions encountered. Unanticipated conditions and inadequate procedures should be reported to the design team along with timely recommendations to solve the problems created. ECA is best qualified to provide this service based on our familiarity with the project, the subsurface conditions, and the intent of the recommendations and design. We wish to remind you that we will store the soil samples for 30 days. The samples will then be discarded unless you request otherwise. We will be happy to discuss our recommendations with you and look forward to providing the additional studies or services necessary to complete this project. We appreciate the opportunity to be of service. Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com APPENDIX A Figures SITE B-1 Soil Boring Location Atlanta, GA - Corporate Headquarters | 1375 Union Hill Industrial Court, Alpharetta, GA 30004 | (770) 667-2040 | www.eca-usa.com APPENDIX B Boring Log Project:Fort Pierce 2Project Location:Fort Pierce, FLProject Number:T1542b Log of Boring B-1 Date(s)Drilled 5/2/2019 DrillingMethod HSA Drill RigType D-57 Groundwater Leveland Date Measured 4.4 feet A.T.D BoreholeBackfill Cuttings Logged By A. Balakrishnan Drill BitSize/Type 2.25 inches DrillingContractor UES SamplingMethod(s)SPT Location Fort Pierce, St Lucie County, Florida Checked By H. Acosta Total Depthof Borehole 60 feet bgs ApproximateSurface Elevation 17 feet A.M.S.L. HammerData 140 Lbs hammer Material TypeFillSPSP SP SP SC SM SM SM SM SM SM SM LL (%)PI (%)SPT N-Values-313238201917 3 13 15 17 7 10 qu (tsf)- Spring TesterUSCS SymbolWater Content (%)-7.0 24.5 - 12.7 - 15.9 - 16.3 - 23.4 22.8 -qu (tsf)MATERIAL DESCRIPTION Grey, fine silty Sand, trace roots, dry (Fill)Dark grey, compact dense poorly graded Sand, dampGrey, compact dense poorly graded Sand with trace organic matter, dampBlack, compact dense poorly graded Sand, trace organic material, dampSame as above, medium compact, dampGrey, medium compact clayey Sand, dampGrey, medium compact silty Sand, trace clay, wetDark grey/black, very loose fine to medium coarse silty Sand, wet Same as above, medium compact, wet Brown, medium compact fine to medium coarse silty Sand, wet Same as above, medium compact, wet Same as above, loose, wet Black, loose fine to medium compact silty Sand with shell fragemnts, dampRec (%) / RQD (%)Depth (feet)0 5 10 15 20 25 30 35 40 Sample Number12 3 4 5 6 7 8 9 10 11 12 13 Sample TypeSampling Resistance, blows/ft-11-12-1915-15-1715-18-2013-10-109-9-106-8-9 2-1-2 4-5-8 5-7-8 5-7-10 4-4-3 3-5-5 L:\ECA\PROJECT\2017proj\T1525 - T1549\T1542b\Engineering\Boring B-1_Ft Pierce 2_T1542b.bg4[ECA Temp.tpl] Sheet 1 of 2Environmental Corp of America1375 Union Hill Industrial Ct. Suite-AAlpharetta, GA 30004(770) 667-2040 Project:Fort Pierce 2Project Location:Fort Pierce, FLProject Number:T1542b Log of Boring B-1 Material TypeSM SM SM SM SM LL (%)PI (%)SPT N-Values100 50/6'' 50/6'' 100 qu (tsf)- Spring TesterUSCS SymbolWater Content (%)21.9 19.6 - 16.7 qu (tsf)MATERIAL DESCRIPTION Black, loose fine to medium compact silty Sand with shell fragemnts, damp Grey, very compact dense fine to medium compact silty Sand with shell fragemnts, damp Same as above, very compact dense, damp Same as above, very compact dense, damp Same as above, very compact dense, damp End of Boring at 60 feet bgs.Rec (%) / RQD (%)Depth (feet)45 50 55 60 Sample Number14 15 16 17 Sample TypeSampling Resistance, blows/ft4-51-49 38-62-50/6'' 58-42-50/6'' 30-53-47 L:\ECA\PROJECT\2017proj\T1525 - T1549\T1542b\Engineering\Boring B-1_Ft Pierce 2_T1542b.bg4[ECA Temp.tpl] Sheet 2 of 2Environmental Corp of America1375 Union Hill Industrial Ct. Suite-AAlpharetta, GA 30004(770) 667-2040 Project:Fort Pierce 2Project Location:Fort Pierce, FLProject Number:T1542b Key to Log of Boring Material TypeLL (%)PI (%)SPT N-Valuesqu (tsf)- Spring TesterUSCS SymbolWater Content (%)qu (tsf)MATERIAL DESCRIPTIONRec (%) / RQD (%)Depth (feet)Sample NumberSample TypeSampling Resistance, blows/ft1 2 3 4 5 6 7 8 9 10 11 12 13 14 COLUMN DESCRIPTIONS 1 Depth (feet): Depth in feet below the ground surface.2 Sample Number: Sample identification number.3 Sample Type: Type of soil sample collected at the depth intervalshown.4 Sampling Resistance, blows/ft: Number of blows to advance drivensampler one foot (or distance shown) beyond seating intervalusing the hammer identified on the boring log.5 SPT N-Values: SPT N-values6Rec (%) / RQD (%): Core Recovery (%) and RQD (%)7 MATERIAL DESCRIPTION: Description of material encountered. May include consistency, moisture, color, and other descriptivetext.8 Material Type: Type of material encountered. 9 USCS Symbol: Graphic depiction of the subsurface materialencountered.10 Water Content (%): Water content of the soil sample, expressed aspercentage of dry weight of sample.11 qu (tsf): Unconfined compression test12qu (tsf)- Spring Tester: Unconfined Compression test value from aspring tester13LL (%): Liquid Limit, expressed as a water content.14 PI (%): Plasticity Index, expressed as a water content. FIELD AND LABORATORY TEST ABBREVIATIONS CHEM: Chemical tests to assess corrosivityCOMP: Compaction testCONS: One-dimensional consolidation testLL: Liquid Limit, percent PI: Plasticity Index, percentSA: Sieve analysis (percent passing No. 200 Sieve)UC: Unconfined compressive strength test, Qu, in ksfWA: Wash sieve (percent passing No. 200 Sieve) MATERIAL GRAPHIC SYMBOLS AF Clayey SAND (SC) Silty SAND (SM) Poorly graded SAND (SP) TYPICAL SAMPLER GRAPHIC SYMBOLS Auger sampler Bulk Sample3-inch-OD California w/brass ringsCME Sampler Grab Sample HQ Rock Core2.5-inch-OD ModifiedCalifornia w/ brass linersNQ Rock Core Pitcher Sample2-inch-OD unlined splitspoon (SPT)Shelby Tube (Thin-walled,fixed head) OTHER GRAPHIC SYMBOLS Water level (at time of drilling, ATD) Water level (after waiting)Minor change in material properties within astratumInferred/gradational contact between strata ?Queried contact between strata GENERAL NOTES 1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may begradual. Field descriptions may have been modified to reflect results of lab tests.2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representativeof subsurface conditions at other locations or times.L:\ECA\PROJECT\2017proj\T1525 - T1549\T1542b\Engineering\Boring B-1_Ft Pierce 2_T1542b.bg4[ECA Temp.tpl]Sheet 1 of 1Environmental Corp of America1375 Union Hill Industrial Ct. Suite-AAlpharetta, GA 30004(770) 667-2040